Numerical simulations of a pyrotechnic shock test

Launch vehicles and spacecraft's use a certain number of pyrotechnic devices during their missions. During flights, stages and boosters separation of the launcher are performed by means of fast cutting devices using high explosive charges (electro-explosive devices or EED). Detonation of these cutting devices produces a so-called pyrotechnic shock which causes the dynamic loading of the launcher structure and its components. In order to verify critical components, such as electro-pneumatic components, it is necessary to perform pyrotechnic shock qualification tests. Nowadays, engineers work by try and error in order to reach the pyroshock test specifications required by launch vehicles and spacecraft's designers. This can lead to the realisation of many preliminary tests and becomes time consuming and expensive. This paper deals with the numerical simulation of the pyroshock test using the finite element code ANSYS-AUTODYN®. For this work, the test setup consists of a steel resonant plate subjected to a free air blast load. The dynamic response of the plate is recorded by means of a set of shock accelerometers located on the upper surface. This paper focuses on the analysis of parameters that can have any influence on the shock response spectrum (SRS) such as mesh size, number of blast loading zones, peak pressure time and the arrival time. The obtained results show that all these four parameters influence the SRS and that the choice of a good set of parameters can lead to a good correspondence between numerical and experimental results.